植物生态学报 ›› 2019, Vol. 43 ›› Issue (2): 119-130.DOI: 10.17521/cjpe.2018.0269

• 研究论文 • 上一篇    下一篇

基于根系发育分级的砂壤土下成熟林木根系构型分析

祝维1,余立璇1,赵德海2,贾黎明1,*()   

  1. 1 北京林业大学省部共建森林培育与保护教育部重点实验室, 北京 100083
    2 Warnell School of Forestry and Natural Resources, The University of Georgia, Athens, GA 30602, USA
  • 收稿日期:2018-10-30 接受日期:2019-01-30 出版日期:2019-02-20 发布日期:2019-06-04
  • 通讯作者: 贾黎明
  • 基金资助:
    国家重点研发计划(2016YFD0600403)

Architectural analysis of root systems of mature trees in sandy loam soils using the root development classification

ZHU Wei1,YU Li-Xuan1,ZHAO De-Hai2,JIA Li-Ming1,*()   

  1. 1 Ministry of Education Key Laboratory of Silviculture and Conservation, Beijing Forestry University, Beijing 100083, China
    2 Warnell School of Forestry and Natural Resources, The University of Georgia, Athens, GA 30602, USA
  • Received:2018-10-30 Accepted:2019-01-30 Online:2019-02-20 Published:2019-06-04
  • Contact: JIA Li-Ming
  • Supported by:
    Supported by the National Key R&D Program of China (2016YFD0600403)(2016YFD0600403)

摘要:

基于根系发育分级标准分析不同等级根系的形态特征和各级根系的生长发育策略, 可以为未来成熟林木根系预测和模型构建提供参考。该研究以30多年生的两个毛白杨(Populus tomentosa)和一个刺槐(Robinia pseudoacacia)的根系系统为研究对象, 通过全挖法获取研究材料, 以Rose (1983)提出的发育分级标准作为根系分级标准, 分析了不同等级根系的基径、根长、连结长度、根系数量等形态特征以及不同等级根系间的拓扑关系。研究结果表明: 1) 3个根系系统的修正拓扑指数qaqb均接近于0, 拓扑指数TI均接近于0.5, 说明3个根系系统均呈现叉状分支; 3个根系系统垂直分布最深达到5.7-6.4 m, 水平分布最长达到7.6-13.5 m; 同一树种根系存在连生关系。2) 3个根系系统能够分支到7-8级根; 一级根基径和长度显著高于后几级根, 一级根基径是后几级根的5.79-36.92倍, 一级根长度是后几级根的1.45-9.11倍; 根系数量随着根系等级增加先增后减, 在三级根上达到最大值。3)在前三级根中, 各级根上的连结长度从根基到根尖变化不大, 说明子级根在母级根上分布均匀, 能够充分高效地吸收土壤资源。4)母级根对子级根的基径拟合线性方程斜率, 一级根最小(平均斜率0.15), 二级根和三级根的斜率相差不大(平均斜率0.34、0.35), 说明一级根优先发育自身直径, 达到锚固和支撑的作用, 二、三级根则会优先发育子级根, 通过不断增强子级根以达到高效占领土壤空间的目的。5)基径对长度的拟合线性方程斜率随着根系等级增加而增加(平均斜率从10.46增长至90.43), 说明高级别根系会倾向于发展根系长度来达到探索资源、拓展空间的目的。

关键词: 发育分级标准, 根系分级, 根系构型, 成熟林木, 砂壤土

Abstract: <i>Aims</i>

Understanding the differences in root architectural strategies among the species and the differences in morphological characteristics among different root orders will facilitate our understanding root growth and development strategies, and thus provide a basis for predicting and modeling the root systems for mature trees. In this study, we analyzed the morphological characteristics and topological relationships for the root systems of two Populus tomentosa trees and one Robinia pseudoacacia tree.

<i>Methods</i>

A method combining both excavation and analysis was applied to extract and quantify root architectural characteristics of the three root systems. The morphological characteristics such as root basal diameter, root length, link length, and root number of different root orders were described using the developmental analysis method of Rose (1983), and their topological relationships were analyzed.

<i>Important findings</i>

1) The modified topological indices qa and qb were close to 0, and the topological index TI was close to 0.5 for all three root systems, indicating their dichotomous structure. The depth and width of the systems ranged from 5.7 to 6.4 m and from 7.6 to 13.5 m, respectively. Root grafts occurred in the same species. 2) The root systems could have the seventh or eighth order roots. The basal root diameter and root length significantly decreased with increasing root order. The first order roots had 5.79-36.92 times the basal diameter and 1.45-9.11 times the length of higher order roots. With increasing root order, the root number increased, and reached a maximum value for the third order roots, and then decreased. 3) In roots of each of the first three orders, the link length varied little from the root base towards its tip, indicating that the child roots were distributed evenly on their parent roots and thus help trees absorb soil resources more efficiently. 4) The regression of basal diameters of child roots on basal diameters of their mother roots showed that the smallest slope for the first order roots (average slope 0.15) and no big difference in the slope between the second and third order roots (0.34 versus 0.35). This suggested that the first order roots developed their own diameter first for anchoring and supporting the tree, while the second and third order roots developed their child roots to facilitate nutrient uptake from the soil. 5) The regression of root length on root basal diameter suggested that the slope increased from 10.46 to 90.43 with increasing root order, which implies that the higher order roots tended to develop their length to explore resources and expand their space.

Key words: developmental classification standard, root system classification, root architecture, mature tree, sandy loam soil